Hello Robert, RD> Thanks for your response. I'm actually completely confused as RD> to what you're doing. I notice you're using __COUNTER__, however RD> couldn't I just use __COUNTER__ without boost? What would the code RD> look like for that? Read documentation about slot usage here: http://boost.org/libs/preprocessor/doc/ref/slot.html and here: http://boost.org/libs/preprocessor/doc/index.html RD> I don't understand the need for this patch to the boost counter library. You can't use built-in counter __COUNTER__ with BOOST_PP_ASSIGN_SLOT, because it autoincrements in point of use. To avoid this patch adding BOOST_PP_ASSIGN_SLOT_BUILTIN_COUNTER macro which works correctly with __COUNTER__. For details read README_*.txt attached to patch. -- Best regards, Andry mailto:andry@inbox.ru